2 * Copyright (c) 2007, 2008 Edward Tomasz NapieraĆa <trasz@FreeBSD.org>
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31 * Public interface declaration for libsmf, Standard MIDI File format library.
36 * \page libsmf libsmf - general usage instructions
38 * An smf_t structure represents a "song". Every valid smf contains one or more tracks.
39 * Tracks contain zero or more events. Libsmf doesn't care about actual MIDI data, as long
40 * as it is valid from the MIDI specification point of view - it may be realtime message,
43 * The only field in smf_t, smf_track_t, smf_event_t and smf_tempo_t structures your
44 * code may modify is event->midi_buffer and event->midi_buffer_length. Do not modify
45 * other fields, _ever_. You may read them, though. Do not declare static instances
46 * of these types, i.e. never do something like this: "smf_t smf;". Always use
47 * "smf_t *smf = smf_new();". The same applies to smf_track_t and smf_event_t.
49 * Say you want to load a Standard MIDI File (.mid) file and play it back somehow.
50 * This is (roughly) how you do this:
56 * smf = smf_load(file_name);
58 * Whoops, something went wrong.
62 * while ((event = smf_get_next_event(smf)) != NULL) {
63 * if (smf_event_is_metadata(event))
66 * wait until event->time_seconds.
67 * feed_to_midi_output(event->midi_buffer, event->midi_buffer_length);
74 * Saving works like this:
88 * for (int i = 1; i <= number of tracks; i++) {
89 * track = smf_track_new();
90 * if (track == NULL) {
95 * smf_add_track(smf, track);
97 * for (int j = 1; j <= number of events you want to put into this track; j++) {
98 * event = smf_event_new_from_pointer(your MIDI message, message length);
99 * if (event == NULL) {
104 * smf_track_add_event_seconds(track, event, seconds since start of the song);
108 * ret = smf_save(smf, file_name);
110 * Whoops, saving failed for some reason.
118 * There are two basic ways of getting MIDI data out of smf - sequential or by track/event number.
119 * You may mix them if you need to. First one is used in the example above - seek to the point
120 * from which you want the playback to start (using smf_seek_to_seconds(), smf_seek_to_pulses()
121 * or smf_seek_to_event()) and then do smf_get_next_event() in loop, until it returns NULL.
122 * Calling smf_load() causes the smf to be rewound to the start of the song.
124 * Getting events by number works like this:
128 * smf_track_t *track = smf_get_track_by_number(smf, track_number);
129 * smf_event_t *event = smf_track_get_event_by_number(track, event_number);
133 * To create new event, use smf_event_new(), smf_event_new_from_pointer() or
134 * smf_event_new_from_bytes(). First one creates an empty event - you need to manually allocate
135 * (using malloc(3)) buffer for MIDI data, write MIDI data into it, put the address of that
136 * buffer into event->midi_buffer, and the length of MIDI data into event->midi_buffer_length.
137 * Note that deleting the event (using smf_event_delete()) will free the buffer.
139 * Second form does most of this for you: it takes an address of the buffer containing MIDI data,
140 * allocates storage and copies MIDI data into it.
142 * Third form is useful for manually creating short events, up to three bytes in length, for
143 * example Note On or Note Off events. It simply takes three bytes and creates MIDI event
144 * containing them. If you need to create MIDI message that takes only two bytes, pass -1 as
145 * the third byte. For one byte message (System Realtime), pass -1 as second and third byte.
147 * To free an event, use smf_event_delete().
149 * To add event to the track, use smf_track_add_event_delta_pulses(), smf_track_add_event_pulses(),
150 * or smf_track_add_event_seconds(). The difference between them is in the way you specify the
151 * time of the event - with the first one, you specify it as an interval, in pulses, from the
152 * previous event in this track; with the second one, you specify it as pulses from the start
153 * of the song, and with the last one, you specify it as seconds from the start of the song.
154 * Obviously, the first version can only append events at the end of the track.
156 * To remove an event from the track it's attached to, use smf_event_remove_from_track().
157 * You may want to free the event (using smf_event_delete()) afterwards.
159 * To create new track, use smf_track_new(). To add track to the smf, use smf_add_track().
160 * To remove track from its smf, use smf_track_remove_from_smf(). To free the track structure,
161 * use smf_track_delete().
163 * Note that libsmf keeps things consistent. If you free (using smf_track_delete()) a track
164 * that is attached to an smf and contains events, libsmf will detach the events, free them,
165 * detach the track, free it etc.
167 * Tracks and events are numbered consecutively, starting from one. If you remove a track
168 * or event, the rest of tracks/events will get renumbered. To get the number of a given
169 * event in its track, use event->event_number. To get the number of track in its smf, use
170 * track->track_number. To get the number of events in the track, use track->number_of_events.
171 * To get the number of tracks in the smf, use smf->number_of_tracks.
173 * In SMF File Format, each track has to end with End Of Track metaevent. If you load SMF file
174 * using smf_load(), that will be the case. If you want to create or edit an SMF, you don't
175 * need to worry about EOT events; libsmf automatically takes care of them for you. If you
176 * try to save an SMF with tracks that do not end with EOTs, smf_save() will append them.
177 * If you try to add event that happens after EOT metaevent, libsmf will remove the EOT.
178 * If you want to add EOT manually, you can, of course, using smf_track_add_eot_seconds()
179 * or smf_track_add_eot_pulses().
181 * Each event carries three time values - event->time_seconds, which is seconds since
182 * the start of the song, event->time_pulses, which is PPQN clocks since the start of
183 * the song, and event->delta_pulses, which is PPQN clocks since the previous event
184 * in that track. These values are invalid if the event is not attached to the track.
185 * If event is attached, all three values are valid. Time of the event is specified when
186 * adding the event (using smf_track_add_event_seconds(), smf_track_add_event_pulses() or
187 * smf_track_add_event_delta_pulses()); the remaining two values are computed from that.
189 * Tempo related stuff happens automatically - when you add a metaevent that is Tempo PropertyChange or
190 * Time Signature, libsmf adds that event to the tempo map. If you remove Tempo PropertyChange event
191 * that is in the middle of the song, the rest of the events will have their event->time_seconds
192 * recomputed from event->time_pulses before smf_event_remove_from_track() function returns.
193 * Adding Tempo PropertyChange in the middle of the song works in a similar way.
195 * MIDI data (event->midi_buffer) is always kept in normalized form - it always begins with
196 * status byte (no running status), there are no System Realtime events embedded in them etc.
197 * Events like SysExes are in "on the wire" form, without embedded length that is used in SMF
198 * file format. Obviously libsmf "normalizes" MIDI data during loading and "denormalizes" (adding
199 * length to SysExes, escaping System Common and System Realtime messages etc) during writing.
201 * Note that you always have to first add the track to smf, and then add events to the track.
202 * Doing it the other way around will trip asserts. Also, try to add events at the end of the
203 * track and remove them from the end of the track, that's much more efficient.
205 * All the libsmf functions have prefix "smf_". First argument for routines whose names start
206 * with "smf_event_" is "smf_event_t *", for routines whose names start with "smf_track_" -
207 * "smf_track_t *", and for plain "smf_" - "smf_t *". The only exception are smf_whatever_new
208 * routines. Library does not use any global variables and is thread-safe, as long as you
209 * don't try to work on the same SMF (smf_t and its descendant tracks and events) from several
210 * threads at once without protecting it with mutex. Library depends on glib and nothing else.
211 * License is BSD, two clause, which basically means you can use it freely in your software,
212 * both Open Source (including GPL) and closed source.
227 #if defined(__GNUC__) && __GNUC__ >= 4
228 #define WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
230 #define WARN_UNUSED_RESULT
233 /** Represents a "song", that is, collection of one or more tracks. */
237 /** These fields are extracted from "division" field of MThd header.
238 * Valid is _either_ ppqn or frames_per_second/resolution. */
240 int frames_per_second;
242 int number_of_tracks;
244 /** These are private fields using only by loading and saving routines. */
247 size_t file_buffer_length;
248 size_t next_chunk_offset;
249 int expected_number_of_tracks;
251 /** Private, used by smf.c. */
252 GPtrArray *tracks_array;
253 double last_seek_position;
255 /** Private, used by smf_tempo.c. */
256 /** Array of pointers to smf_tempo_struct. */
257 GPtrArray *tempo_array;
260 typedef struct smf_struct smf_t;
262 /** Describes a single tempo or time signature change. */
263 struct smf_tempo_struct {
266 int microseconds_per_quarter_note;
269 int clocks_per_click;
273 typedef struct smf_tempo_struct smf_tempo_t;
275 /** Represents a single track. */
276 struct smf_track_struct {
280 size_t number_of_events;
282 /** These are private fields using only by loading and saving routines. */
284 size_t file_buffer_length;
285 int last_status; /* Used for "running status". */
287 /** Private, used by smf.c. */
288 /** Offset into buffer, used in parse_next_event(). */
289 size_t next_event_offset;
290 size_t next_event_number;
292 /** Absolute time of next event on events_queue. */
293 size_t time_of_next_event;
294 GPtrArray *events_array;
297 typedef struct smf_track_struct smf_track_t;
299 /** Represents a single MIDI event or metaevent. */
300 struct smf_event_struct {
301 /** Pointer to the track, or NULL if event is not attached. */
304 /** Number of this event in the track. Events are numbered consecutively, starting from 1. */
307 /** Note that the time fields are invalid, if event is not attached to a track. */
308 /** Time, in pulses, since the previous event on this track. */
309 int32_t delta_time_pulses;
311 /** Time, in pulses, since the start of the song. */
314 /** Time, in seconds, since the start of the song. */
317 /** Tracks are numbered consecutively, starting from 1. */
320 /** Pointer to the buffer containing MIDI message. This is freed by smf_event_delete. */
321 uint8_t *midi_buffer;
323 /** Length of the MIDI message in the buffer, in bytes. */
324 size_t midi_buffer_length;
327 typedef struct smf_event_struct smf_event_t;
329 /* Routines for manipulating smf_t. */
330 smf_t *smf_new(void) WARN_UNUSED_RESULT;
331 void smf_delete(smf_t *smf);
333 int smf_set_format(smf_t *smf, int format) WARN_UNUSED_RESULT;
334 int smf_set_ppqn(smf_t *smf, uint16_t ppqn) WARN_UNUSED_RESULT;
336 char *smf_decode(const smf_t *smf) WARN_UNUSED_RESULT;
338 smf_track_t *smf_get_track_by_number(const smf_t *smf, int track_number) WARN_UNUSED_RESULT;
340 smf_event_t *smf_peek_next_event(smf_t *smf) WARN_UNUSED_RESULT;
341 smf_event_t *smf_get_next_event(smf_t *smf) WARN_UNUSED_RESULT;
342 void smf_skip_next_event(smf_t *smf);
344 void smf_rewind(smf_t *smf);
345 int smf_seek_to_seconds(smf_t *smf, double seconds) WARN_UNUSED_RESULT;
346 int smf_seek_to_pulses(smf_t *smf, size_t pulses) WARN_UNUSED_RESULT;
347 int smf_seek_to_event(smf_t *smf, const smf_event_t *event) WARN_UNUSED_RESULT;
349 size_t smf_get_length_pulses(const smf_t *smf) WARN_UNUSED_RESULT;
350 double smf_get_length_seconds(const smf_t *smf) WARN_UNUSED_RESULT;
351 int smf_event_is_last(const smf_event_t *event) WARN_UNUSED_RESULT;
353 void smf_add_track(smf_t *smf, smf_track_t *track);
354 void smf_track_remove_from_smf(smf_track_t *track);
356 /* Routines for manipulating smf_track_t. */
357 smf_track_t *smf_track_new(void) WARN_UNUSED_RESULT;
358 void smf_track_delete(smf_track_t *track);
360 smf_event_t *smf_track_get_next_event(smf_track_t *track) WARN_UNUSED_RESULT;
361 smf_event_t *smf_track_get_event_by_number(const smf_track_t *track, size_t num) WARN_UNUSED_RESULT;
362 smf_event_t *smf_track_get_last_event(const smf_track_t *track) WARN_UNUSED_RESULT;
364 void smf_track_add_event_delta_pulses(smf_track_t *track, smf_event_t *event, uint32_t delta);
365 void smf_track_add_event_pulses(smf_track_t *track, smf_event_t *event, size_t pulses);
366 void smf_track_add_event_seconds(smf_track_t *track, smf_event_t *event, double seconds);
367 int smf_track_add_eot_delta_pulses(smf_track_t *track, uint32_t delta) WARN_UNUSED_RESULT;
368 int smf_track_add_eot_pulses(smf_track_t *track, size_t pulses) WARN_UNUSED_RESULT;
369 int smf_track_add_eot_seconds(smf_track_t *track, double seconds) WARN_UNUSED_RESULT;
370 void smf_event_remove_from_track(smf_event_t *event);
372 /* Routines for manipulating smf_event_t. */
373 smf_event_t *smf_event_new(void) WARN_UNUSED_RESULT;
374 smf_event_t *smf_event_new_from_pointer(const void *midi_data, size_t len) WARN_UNUSED_RESULT;
375 smf_event_t *smf_event_new_from_bytes(int byte1, int byte2, int byte3) WARN_UNUSED_RESULT;
376 smf_event_t *smf_event_new_textual(int type, const char *text);
377 void smf_event_delete(smf_event_t *event);
379 int smf_event_is_valid(const smf_event_t *event) WARN_UNUSED_RESULT;
380 int smf_event_is_metadata(const smf_event_t *event) WARN_UNUSED_RESULT;
381 int smf_event_is_system_realtime(const smf_event_t *event) WARN_UNUSED_RESULT;
382 int smf_event_is_system_common(const smf_event_t *event) WARN_UNUSED_RESULT;
383 int smf_event_is_sysex(const smf_event_t *event) WARN_UNUSED_RESULT;
384 int smf_event_is_eot(const smf_event_t *event) WARN_UNUSED_RESULT;
385 int smf_event_is_textual(const smf_event_t *event) WARN_UNUSED_RESULT;
386 char *smf_event_decode(const smf_event_t *event) WARN_UNUSED_RESULT;
387 char *smf_event_extract_text(const smf_event_t *event) WARN_UNUSED_RESULT;
389 /* Routines for dealing with Variable Length Quantities (VLQ's).
390 Slightly odd names reflect original static names within libsmf
392 int smf_format_vlq (unsigned char *buf, int length, unsigned long value);
393 int smf_extract_vlq(const unsigned char *buf, const size_t buffer_length, uint32_t *value, uint32_t *len);
395 /* Routines for loading SMF files. */
396 smf_t *smf_load(FILE *) WARN_UNUSED_RESULT;
397 smf_t *smf_load_from_memory(void *buffer, const size_t buffer_length) WARN_UNUSED_RESULT;
399 /* Routine for writing SMF files. */
400 int smf_save(smf_t *smf, FILE *file) WARN_UNUSED_RESULT;
402 /* Routines for manipulating smf_tempo_t. */
403 smf_tempo_t *smf_get_tempo_by_pulses(const smf_t *smf, size_t pulses) WARN_UNUSED_RESULT;
404 smf_tempo_t *smf_get_tempo_by_seconds(const smf_t *smf, double seconds) WARN_UNUSED_RESULT;
405 smf_tempo_t *smf_get_tempo_by_number(const smf_t *smf, size_t number) WARN_UNUSED_RESULT;
406 smf_tempo_t *smf_get_last_tempo(const smf_t *smf) WARN_UNUSED_RESULT;
408 const char *smf_get_version(void) WARN_UNUSED_RESULT;